Identification of calcium-binding proteins associated with the human sperm plasma membrane

<p>Abstract</p> <p>Background</p> <p>The precise composition of the human sperm plasma membrane, the molecular interactions that define domain specific functions, and the regulation of membrane associated proteins during the capacitation process, still remain to be fully understood. Here, we investigated the repertoire of calcium-regulated proteins associated with the human sperm plasma membrane.</p> <p>Methods</p> <p>Surface specific radioiodination was combined with two-dimensional gel electrophoresis, a 45Ca-overlay assay, computer assisted image analysis and mass spectrometry to identify calcium-binding proteins exposed on the human sperm surface.</p> <p>Results</p> <p>Nine acidic 45Ca-binding sperm proteins were excised from stained preparative 2D gels and identified by mass spectrometry. Five of the calcium binding proteins; HSPA2 (HSP70-1), HSPA5 (Bip), HYOU1 (ORP150), serum amyloid P-component (SAP) and protein kinase C substrate 80K-H (80K-H) were found to be accessible to Iodo-Bead catalyzed 125I-labelling on the surface of intact human sperm. Agglutination and immunofluorescence analysis confirmed that SAP is situated on the plasma membrane of intact, motile sperm as well as permeabilized cells. Western blot analysis showed increased phosphorylation of human sperm 80K-H protein following in vitro capacitation. This is the first demonstration of the 80K-H protein in a mammalian sperm.</p> <p>Conclusion</p> <p>The presence of SAP on the surface of mature sperm implies that SAP has a physiological role in reproduction, which is thought to be in the removal of spermatozoa from the female genital tract via phagocytosis. Since 80K-H is a Ca2+-sensor recently implicated in the regulation of both inositol 1,4,5-trisphosphate receptor and transient receptor potential (TRP) cation channel activities, its detection in sperm represents the first direct signaling link between PKC and store-operated calcium channels identified in human sperm.</p

Cystinosis: practical tools for diagnosis and treatment

Cystinosis is the major cause of inherited Fanconi syndrome, and should be suspected in young children with failure to thrive and signs of renal proximal tubular damage. The diagnosis can be missed in infants, because not all signs of renal Fanconi syndrome are present during the first months of life. In older patients cystinosis can mimic idiopathic nephrotic syndrome due to focal and segmental glomerulosclerosis. Measuring elevated white blood cell cystine content is the corner stone for the diagnosis. The diagnosis is confirmed by molecular analysis of the cystinosin gene. Corneal cystine crystals are invariably present in all patients with cystinosis after the age of 1 year. Treatment with the cystine depleting drug cysteamine should be initiated as soon as possible and continued lifelong to prolong renal function survival and protect extra-renal organs. This educational feature provides practical tools for the diagnosis and treatment of cystinosis

Survey of Venlo 1995 - VSO

Survey among the inhabitants of Venlo, concerning cultural and welfare facilities. Use and appreciation of cultural facilities of Venlo, like: museums, school of music, ballet, art library, children's farm, adult education centre, carnival procession, summer festivals, feasts of St. Nicholas and St. Martin, regional cultural activities, theatre, public library, community centres / lack of certain cultural facilities / membership of clubs / r.'s opinion about the surveys held by the municipality and suggestions for questions to ask in next surveys / wishes with regard to policy of municipality / use and appreciation of welfare services of Venlo for various groups of inhabitants / participation in volunteer work, suggestions to encourage volunteer work / r.'s opinion about district level policy of the municipality. Background variables: basic characteristics/ place of birth/ residence/ household characteristics/ characteristics of parental family/household/ occupation/employment/ income/capital assets/ education/ politics/ religio

Venlo survey 1999 - VSO

Satisfaction of neighbourhood services / problems in the neighbourhood: theft, vandalism, noise, threats, graffiti, harassment, dirt, dog-shit, burglary, violence, drugs / livability of neighbourhood, quality of living / quality of housing, housing situation / feelings of unsafety / victimization / image of the neighbourhood / image of the city / local democracy, information Background variables: basic characteristics/ place of birth/ residence/ housing situation/ household characteristics/ occupation/employment/ education/ consumption of durable

Survey Venlo 2000 - VSO

Survey among inhabitants of Venlo Satisfaction with municipal services / cleaning of the city / quality of the city centre / facilities for cyclists / environmental issues Background variables: basic characteristics/ housing situation/ occupation/employment/ educatio

City survey Venlo 1997 - VSO

Survey among inhabitants of Venlo. Satisfaction with facilities in district where respondent is living / problems and petty crime in district / quality of life in district / quality of housing / feelings of insecurity / victimization during last 12 months / image of district and city / municipal swimming pool / community center De Staay Blerick Background variables: basic characteristics/ place of birth/ household characteristics/ occupation/employment/ income/capital assets/ educatio